Agricultural implements that engage the ground, such as planters, harrows and rakes, are often formed in several laterally disposed sections. These sections are pivotally connected to each other for several reasons. First, and due to the great width of the implement, they cannot be pulled along a road without blocking several lanes of traffic unless they can be folded. Second, and also due to their great width, they cannot follow the ground contours of the field unless some vertical pivoting about a longitudinal axis of each section with respect to its adjacent sections is provided.
Implements formed as a series of laterally disposed, pivotally coupled sections suffer from several problems. First, they are difficult to turn. When traveling on the road, turning is not a serious problem since the wings can be completely pivoted to a position above a center section having a center frame, and the center frame can be supported on two or more support wheels. This arrangement permits easy turning. This folding process takes a great deal of time and thus is impractical to perform when turning at the end of each row in the field. At the end of the day, when the farmer has finished working a field, he can engage hydraulic cylinders that gradually lift the wings into this folded position. This may require releasing or engaging various linkages, making or breaking certain hydraulic connections, and emptying certain of the ground engaging tools on the wings that contain fertilizer, herbicides or seed. In short, converting the vehicle into an easy turning roadable configuration takes many minutes and may require the farmer to leave the cab of the vehicle. In a field of 200 acres, for example, the farmer may have to spend more time turning the vehicle at the ends of rows than he would spend actually working the ground.
A partial solution to the problem of difficult turning is to raise the wings about their pivot points, but only slightly. Typically, the hydraulic cylinders that raise the wings are engaged for a limited amount of time to lift the wings only slightly above the ground. This process can be performed in a matter of a few seconds and does not require the farmer to leave the vehicle. It also does not require the time consuming mechanical and hydraulic manual manipulations of the implement.
A second problem that implements with wings have is difficulty in properly distributing the weight of the implement equally over all the ground contacting tools. The center section of the implement typically includes a variety of additional components such as wheels, hydraulic motors, cylinders, bins, hoppers and towing tongue that are not found on the wing sections. A greater downwardly disposed force is applied by the collective weight of these components to each of the ground engaging tools supported on the center section than to those supported by the wings. As a result, the ground engaging tools supported on the center frame penetrate the ground to a greater extent. The center frame also applies a downwardly disposed force to the pivoted inner ends of the wings that it is connected to. This tends to force the inner ends of the wings downward and tends to allow a resistance of the soil to being penetrated to lift the outer, free, ends of the wings upward. The end result of this weight imbalance, then, is to prevent all the ground engaging tools on the center frame and on the wings from penetrating the ground to an equal depth.
One solution that has been proposed to this weight imbalance or "down pressure" problem is to add springs to the implement coupled between the center frame and the wings that are biased to pull the wings downward with respect to the center frame. In this manner, some of the weight of the center frame will be transferred to the wings and the ground engaging tools on the center frame and the on wings will tend to have a more nearly equal weight distribution.
Providing an implement having spring-based down pressure biasing of implement wings with hydraulic cylinders used to lift the wings slightly during turns in the field is difficult, and requires a complicated arrangement of linkages, cylinders and springs.
It would be beneficial, therefore, to provide an improved agricultural vehicle and implement arrangement with a wing lift and down pressure control. It is an object of this invention to provide such a improved system.